After increasing slightly in recent decades, the sea ice extent around Antarctica plummeted in 2016. Credit: Malte Stuecker/University of Washington

While winter sea ice in the Arctic is declining so dramatically that ships can now navigate those waters without any icebreaker escort, the scene in the Southern Hemisphere is very different. Sea ice area around Antarctica has actually increased slightly in winter—that is, until last year.

A dramatic drop in Antarctic sea ice almost a year ago, during the Southern Hemisphere spring, brought its maximum area down to its lowest level in 40 years of record keeping. Ocean temperatures were also unusually warm. This exceptional, sudden nosedive in Antarctica differs from the long-term decline in the Northern Hemisphere. A new University of Washington study shows that the lack of Antarctic sea ice in 2016 was in part due to a unique one-two punch from atmospheric conditions both in the tropical Pacific Ocean and around the South Pole.

The study was published Aug. 24 in Geophysical Research Letters.

"This combination of factors, all these things coming together in a single year, was basically the 'perfect storm,' for Antarctic sea ice," said corresponding author Malte Stuecker, a UW postdoctoral researcher in atmospheric sciences. "While we expect a slow decline in the future from global warming, we don't expect such a rapid decline in a single year to happen very often."

The area of sea ice around Antarctica at its peak in late 2016 was 2 million square kilometers (about 800,000 square miles) less than the average from the satellite record. Statistically, this is three standard deviations away from the average—an event that would be expected to occur randomly just once every 300 years.

The record low was not predicted by climate scientists, so UW researchers looked at the bigger picture in ocean and atmospheric data to explain why it happened.

The previous year, 2015-16, had a very strong El Niño in the tropical Pacific Ocean. Nicknamed the "Godzilla El Nino," the event was similar to other monster El Niños in 1982-83 and 1997-98. Unlike the 1997-98 event, however, it was only followed by a relatively weak La Niña in 2016.

Far away from the tropics, the tropical El Niño pattern creates a series of high- and low-pressure zones that cause unusually warm ocean temperatures in Antarctica's eastern Ross, Amundsen and Bellingshausen seas. But in 2016, when no strong La Niña materialized, researchers found that these unusually warm surface pools lingered longer than usual and affected freeze-up of seawater the following season.

The percent of ocean surface covered with sea ice in 2016 was lower than usual (brown) over many parts of the Southern Ocean. The black line shows the edge of the region with at least 15 percent ice cover. Credit: Malte Stuecker/University of Washington

"I've spent many years working on tropical climate and El Niño, and it amazes me to see its far-reaching impacts," Stuecker said.

Meanwhile, observations show that the winds circling Antarctica were unusually weak in 2016, meaning they did not push sea ice away from the Antarctic coast to make room for the formation of new ice. This affected ice formation around much of the Southern Ocean.

"This was a really rare combination of events, something that we have never seen before in the observations," Stuecker said.

The researchers analyzed 13,000 years of climate model simulations to study how these unique conditions would affect the sea ice. Taken together, the El Niño pattern and Southern Ocean winds explain about two-thirds of the 2016 decline. The rest may be due to unusually big storms, which a previous paper suggested had broken up ice floes.

Scientists predict Antarctica's ocean will be one of the last places on Earth to experience global warming. Eventually the Southern Ocean's surface will begin to warm, however, and then sea ice there will begin its more long-term decline.

"Our best estimate of the Antarctic sea ice turnaround point is sometime in the next decade, but with high uncertainty because the climate signal is small compared to the large variations that can occur from one year to the next," said co-author Cecilia Bitz, a UW professor of atmospheric sciences.

Stuecker noted that this type of big, rare weather event is useful to help understand the physics behind sea ice formation, and to learn how best to explain the observations.

"For understanding the climate system we must combine the atmosphere, ocean and ice, but we must focus on more than a specific region," Stuecker said. "If we want to understand sea ice in Antarctica, we cannot just zoom in locally—we really have to take a global perspective."

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And so begins the death spiral of the Antarctic ice, to match that of the Arctic. This week's second big climate change reckoning story (see Harvey moving back out into the Gulf of Mexico to make extra rainfall). What will it be next week?

Wonder what the #climatecranks will claim about this one. And how long they'll keep making up excuses for the cookie crumbs on the shirt and the broken jar on the floor.

"While winter sea ice in the Arctic is declining so dramatically that ships can now navigate those waters without any icebreaker escort, the scene in the Southern Hemisphere is very different." Do they mean like Mawson did in 1913?

"Eighty three years ago today, Mawson was sailing along the Antarctic coast. In 2013, global warming nutcases trying to retrace Mawson's route are hoping an icebreaker comes and saves them.Sir DOUGLAS MAWSON'S second expedition on SCOTT'S Discovery to Antarctic waters south of the Indian Ocean and Australia is by this time already near the coast which he skirted and explored in the Summer of 1929-30. He identified Enderby and Kemp Lands, first seen by British explorers a hundred years before.http://query.nyti...448385F9

Antarctic trap: Stranded ship awaiting Australian rescue after Chinese, French turn awayDecember 29, 2013 "The Akademik Shokalskiy, with 74 scientists, tourists and crew members on board.. The voyage was to visit Douglas Mawson's Antarctic huts, which previously couldn't be accessed because of an iceberg." http://rt.com/new...cue-935/

One can wonder if this ignorant charlatan, Chris Turney, gives any thought to what DID not happen in 1912. […]Had the ship carrying the trio of explorers in 1912, the Aurora, gotten icebound the same way the M.V. Akademik Shokalskiy did, there would have been no rescue option and certain death."http://news.natio...rship_r1

I know that I do not need the steaming piece of dog dung, (AKA,Caliban) to tell me if I can comment on a person that the steaming piece of dog dung has never even heard of & therefore knows nothing about."Into the UnknownThey were 31 men at the bottom of the world exploring uncharted territory. What followed was one of the most terrifying survival stories of all time."[…]Another ten months passed before the Aurora returned. When Mawson finally reached Australia in February 1914, he was greeted as a national hero and knighted by King George V. He spent the rest of his career as a professor at the University of Adelaide. Although he would lead two more Antarctic expeditions, his life's work became the production of 96 published reports that embodied the scientific results of the AAE.

I feel the need to fill the steaming piece of dog dung, (AKA,Caliban), in on the significance of Mawson's Australasian Antarctic Expedition, 1911-13. It is doubtful if the wretched creature who, I'm sure sees something like this looking back at him from the mirror, "Jabba, this is your last chance. Free us or die." http://starwars.w...ic_Tiure

has the ability to look at these phots that put into perspective the Cape Denison that Mawson dealt with and the one that these present day explorers saw 100 years later in 2013.

"The week had been eventful, the highlight being two successful journeys by small teams across 65km of ice to carry out research and conservation work on Douglas Mawson's huts at Cape Denison."https://www.thegu...tarctica

I feel the need to fill the steaming piece of dog dung, (AKA,Caliban), in on the significance of Mawson's Australasian Antarctic Expedition, 1911-13.[...] "Jabba, this is your last chance. Free us or die." http://starwars.w...ic_Tiure

has the ability to look at these phots that put into perspective the Cape Denison that Mawson dealt with and the one that these present day explorers saw 100 years later in 2013.

Who cares what the steaming piece of dog dung, (AKA,Caliban) thinks is relevant? What is relevant is that 100 years after Mawson could sail to shore to establish his camp at Commonwealth Bay. "My personal knowledge or lack rgereof regarding your man Mawson is completely irrelevant." Then one might ask why, if you obviously know nothing about this suject, why do you choose to show how stupid you are & comment on it?This is what is called "relevant", you know nothing Jabba look alike idiot."Had the ship carrying the trio of explorers in 1912, the Aurora, gotten icebound the same way the M.V. Akademik Shokalskiy did, there would have been no rescue option and certain death."http://news.natio...tl_ot_w#

The only thing relevant to this article's content is the conditions found, and what factors created those conditions.

The one with no knowledge of anything, probably will fail to see how what follows is "relevant"."Antarctic Sea Ice Reaches New Record Maximum Oct. 8, 2014Sea ice surrounding Antarctica reached a new record high extent this year, covering more of the southern oceans than it has since scientists began a long-term satellite record to map sea ice extent in the late 1970s." http://www.nasa.g...-maximum